Reality In late 1959 cases of a disease that was later to be named Human immunodeficiency virus (HIV) jumped the species barrier from Chimpanzee's(Pan troglodytes troglodytes) to humans in southern Congo. HIV causes the disease acquired immunodeficiency syndrome or AIDS. AIDS is now a pandemic. In 2007, an estimated 33.2 million people lived with the disease worldwide, and it killed an estimated 2.1 million people, including 330,000 children. Over three-quarters of these deaths occurred in sub-Saharan Africa, retarding economic growth and destroying human capital.